Replacing brake and gear cables

Brake cables

1. Check both brakesAny sponginess, fraying at the lever or sticking means replacing the cables. Do both.
2. Release the old cableLoosen the anchor bolt at the brake and pull the cable out from the lever end. Note the end: drop-bar levers use a mushroom (pear) end, flat-bar levers a cylindrical (barrel) end (Sheldon Brown).
3. Check the outer casingReplace it if it's kinked, cracked or squashed at the ends. Cut it with proper cable cutters, not pliers, file the ends square and fit ferrules.
4. Fit the new cableFeed it from the lever, through the casing, to the brake. Pull it firm so there's no slack before you clamp it.
5. Set and testSet the blocks close to the rim (1–2mm a side is a common setting), tighten the anchor bolt, then pull the lever hard several times to bed the cable in and re-adjust. Fit an end cap.

Gear cables

1. Know your systemSturmey-Archer hub gear or derailleur? The cable route and adjustment are different.
2. Slacken the cableDerailleur: shift to the smallest rear sprocket. Sturmey-Archer 3-speed: shift to high gear, where Sheldon Brown says the cable should be totally slack.
3. Remove the old cableLoosen the anchor and pull the cable out. Photograph where any barrel adjuster sits first.
4. Fit the new cableFeed it from the shifter end. Old unlined casing was traditionally run with grease, so a light smear on the inner helps there.
5. Adjust and testUse the barrel adjuster to fine-tune, then test every gear under load. For hub gears, see the Sturmey-Archer guide.

Buying the right cable

• Brake inner cable is thicker than gear inner cable, because it takes more load (Sheldon Brown). Buy the right type.
• Match the end to your levers: mushroom (pear) for drop bars, cylindrical (barrel) for flat bars.
• Brake casing is a tight helix of steel wire. Never use index ('compressionless') gear casing for brakes: Sheldon Brown warns brake loads can make it burst.
• Always fit end caps to the inner cable.